Light, when delivered to the body, has been shown to elicit a wide range of therapeutic effects. Specifically, light can be used as a therapeutic agent for various disorders. Light, in the Ultraviolet (UV) spectrum, may be used as a treatment for skin disorders such as psoriasis, vitiligo, dermatitis, asteatotic, purigo, pruritis, etc. Light therapy is often delivered in a doctor's office or at home in chambers that deliver light to the entire body surface or with smaller light sources for delivery of light to focused areas of the body. Typically, a trained professional is required to deliver the light to ensure that the patient receives the correct dose of light and that sensitive areas, such as the eyes, are not exposed to the light.
In a light chamber, the amount of light delivered is based on the amount of time the patient is exposed to light. The light is delivered to the entire body even though the region that requires treatment often composes a fraction of the overall surface area of the body. When receiving this modality of light therapy, the patient must wear protective eyewear to prevent exposure of light to the eyes. If the patient is exposed to more light than intended, cellular damage and/or burns may occur over a large portion of the body, leading to significant discomfort and even medical treatment.
Using a focused light solves the issue of light exposure to areas that do not need therapy because the user directs the light to the area where the therapy is needed. When therapy is delivered at home and the user controls where the light is being delivered, there is increased risk of overexposure of one area of the body and underexposure of another area. In addition, the light can be inadvertently directed towards sensitive areas such as the eyes or genitals.
Further, there is evidence to show that light therapy treatment for skin disorders has been limited by patient's unwillingness to receive treatment in doctor's offices and lack of adherence to home light therapy systems. Adherence to therapy at home may be improved by increasing patient engagement and improving device ease of use.
Light therapy may also be combined with topical treatments. For example, coal tar is used as a therapeutic in conjunction with (though typically not at the same time) as phototherapy. For example, phototherapy with UVB has been used with coal tar (the Goeckerman regimen) as well as with anthralin. The Goeckerman regimen uses daily treatments of 3 to 4 weeks on average. The coal tar or anthralin is applied once or twice each day and then washed off before the procedure. Studies indicate that a low-dose (e.g., 1%) coal tar preparation is as effective as a high-dose (6%) preparation. Such regimens are unpleasant, but are still useful for some patients with severe psoriasis, because they can achieve long-term remission (up to 18 months on average). Treatments involving both UVB and coal tar or other topical drugs typically involve the separate application of the UVB and coal tar, in part because it coal tar is messy, odiferous and blocks or absorbs all or nearly all of the delivered UV light. For this reason, coal tar is often applied after administration of the UVB. Unfortunately, bifurcating treatment in this way complicates the treatment, and may further limit the effectiveness. In addition, the use of a topical agent such as coal tar may be messy and unpleasant, at least in part because of the odor associated with the agent and the use of oil-based agents (e.g., petroleum) solubilizing the coal tar (or coal tar extract).
Thus, there is a need for apparatuses and methods for phototherapy, particularly for the treatment of skin disorders such as psoriasis, that are easy to use in even a home environment, and otherwise permit the application of therapeutic light to one or more specific areas of a patient's skin. The apparatuses, compositions, and methods described herein may address these concerns.
In addition, it would be beneficial to provide methods of providing phototherapy that permit accurate and effective application of phototherapy every day or every two days (e.g., within approximately 48 hours, or within approximately 24 hours, etc.), or for the application of partial doses, including applying a dose of phototherapy to a patient within a short period of time after a dose phototherapy has been interrupted. Currently such dosing is difficult or impossible in part because it the skin responds dynamically to a phototherapy dose. Typically doses to treat psoriasis (including with coal tar) are applied at or near a minimal erythema dose (MED), and the MED, which it usually determined based on skin type and patient-reported pain/redness, may vary among individuals.
In addition, it would be beneficial to provide one or more dressings that may be used with a light therapy (e.g., UV) applicator to hold the applicator at a fixed position (including at a fixed or known distance) from the patient. Described herein are methods and apparatuses that may address these needs.